Here is a suggestion for a permanent solution to your situation.
I purchased four 2'x2' paving blocks at a big box store. (look for any with chipped corners and ask for a discount.) Park your camper in the desired spot and mark the location of each tire. Move the camper and remove the sod where each tire will sit. Pick one of the four sites as your reference and add gravel/sand tamping it down to create a level surface. Place a paving block there and then do the same for the remaining three blocks leveling each to the reference block. You will have a parking pad that will instantly level your trailer (side to side) every time you park it. Just use the tongue jack to level front to back and your done.